POS1416 LONG-TERM OUTCOME OF SYSTEMIC LUPUS ERYTHEMATOSUS (SLE); DATA FROM THE LARGE POPULATION-BASED SOUTHEAST SLE COHORT (Nor-SLE)
Authors: S. R. Moe, H. Haukeland, T. Garen, A. Orre, G. Wivestad, T. Bøe, H. Øvreås, A. Botea, N. Damjanic, Ø. Molberg, K. Lerang
Journal: Annals of the Rheumatic Diseases (2022)

Background Population-based studies on Systemic Lupus Erythematosus (SLE) patients with a verified diagnosis is considered the gold standard to find true outcomes in SLE, but few population-based SLE cohorts have follow-up over 15 years [1]. Norway is among the few countries worldwide where social and structural factors facilitate the gathering of complete population-based cohorts in rare disease like SLE due to its healthcare organization. Objectives To examine long-term outcome of SLE in a population-based setting and determine if immediate cause of death differs between SLE patients and the general population. Methods The study included all SLE patients who were resident in the Southeast region of Norway during 1999 - 2017 and met the 1997 American College of Rheumatology classification criteria for SLE. All SLE diagnosis was confirmed by chart review. SLE patients and 15 controls for each case (matched by age, gender and ethnicity) were linked to the Norwegian Cause of Death Registry. We examined survival by means of Kaplan-Meyer estimates and used log rank test to test for differences. To estimate risk of death, we performed calculations of standard mortality rate (SMR) by dividing the number of deaths on the number of years observed. The excepted number of deaths referred to the number of deaths for the matched control group. All SLE cases were included in SMR. The 95 % confidence interval (CI) of SMR was calculated with Mid-P exact test. We defined immediate cause of death as the final event directly leading to death. An International Classification of Diseases 10 th revision code of I00-99 or R96 classified as death from cardiovascular disease (CVD) (except pulmonary embolism and cerebral bleeding) and of infections A00-B99, J10-18, N39, M86 or U07. Results We identified 1298 SLE patients in the region, of whom 673 was incident cases; all captures within one year from diagnosis. Of the incident cases, 76 (11%) died during 8434 years of follow-up (Table 1). The five-, ten-, 15- and 20-year survival for incident SLE patients (controls) was respectively 98 (98), 94 (96), 87 (94) and 82 (88) % and differed significantly first after ten years of disease duration compared to controls. Figure 1 shows 20-year survival for incident SLE patients and matched controls; stratified by gender. SMR for all SLE cases was 2.3 (95 % CI 1.5. - 4.0); female SLE 2.5 (95 % CI 1.6 – 3.9) and male SLE 1.9 (95 % CI 1.3 – 2.2). The most common immediate cause of death in SLE patients was CVD; whereof myocardial infarction (21 %) was most frequent. SLE patients died more often of CVD than controls (29 % vs. 21 %, p = 0.01) and had a tendency to more infections (23 % vs. 18 %, p = 0.07), whereof pneumonia (58 %) was most frequent. Table 1. Patient demographics, follow-up time and number of deaths in the total Systemic Lupus Erythematosus (SLE) cohort and in incident SLE patients. Total SLE cohort Incident SLE Female Male n = 1298 n = 577 n = 96 Of European descent, n (%) 1140 (88) 472 (82) 86 (90) Juvenile onset a , n (%) 93 (7) 31 (5) 6 (6) LN b , n (%) 470 (36) 177 (30) 49 (51) Cumulative ACR criteria c , µ (SD) 5.4 (1.2) 5.3 (1.2) 5.1(1.1) Follow-up years, total 19252 6160 1217 Deaths, n (%) 282 (23) 54 (9) 22 (23) Age at diagnosis, years µ (SD) 35.5 (15.7) 37.4 (15.6) 44 (17.9) Disease duration at death, years µ (SD) 20.4 (12.5) 9.6 (5.8) 10.6 (10.5) µ: mean, n: number, SD: standard deviation a Diagnosed before age of 16 b Lupus Nephritis defined by 1999 American College of Rheumatology classification criteria for Systemic Lupus Erythematosus c 1997 American Collee of Rheumatology classification criteria for Systemic Lupus Erythematosus Conclusion Mortality in SLE is substantially increased. Differences in survival compared to the general population only appear after ten years of disease duration. CVD was the most common immediate cause of death and more frequent in SLE patients. References [1]Reppe Moe, S., Haukeland, H., Molberg, Ø., &amp; Lerang, K. (2021). Long-Term Outcome in Systemic Lupus Erythematosus; Knowledge from Population-Based Cohorts. J Clin Med, 10 (19). doi:10.3390/jcm10194306 Disclosure of Interests None declared